aerogel

Aerogel is an advanced man-madesilicon based material developed in the 1930/40s. Comprising of mainly air, it has some astounding material properties.

How is it made:
Aerogel is formed from a silica-dioxidegel. If the liquid in the gel is left to evaporate, the gel collapses. However, by using a process known as supercritical drying, the liquid is evaporated without causing the structure of the gel to collapse and the aerogel retains its material properties. The end result is a light translucent material.

Properties of aerogels include:

Lowest solid density: aerogel is the lightest man-made material with a density only three times that of air

Highest porosity: This material can be up to 95% porosity with the pore size ranging up to micron size.

Very high surface area: Aerogels can have up to 1000 square metres of surface area per one gram

Versatile compositions: Aerogels can be made with a wide range of chemicalcompositions which allows all these properties to be altered to suit.

Just how good is aerogel as an insulator?:
If the aerogel material is filled with air, it has the same insulation capability as 15 cm (6 inches) of fibreglass batting. If it is evacuated (ie no air in the aerogel), it is the equivalent of 97cm (38 inches) of fibreglass batting.

I remember seeing a memorable picture with a 2.5cm (1 inch) thick slab of aerogel sitting upright on a bench. On the left side was a human finger touching the aerogel slab, on the right side has an oxy-acetylene torch trying to burn the aerogel. The human finger found the aerogel quite comfortable to touch!